POWER MEASUREMENT CIRCUIT
A power measurement circuit comprises: a transconductance rectifier arrangement including an input and configured to receive a sinusoidal input voltage signal; and an averaging filter for producing a time averaged DC output signal proportional to the mean square of the voltage at the input of the transconductance rectifier arrangement and representative of the average power of the input voltage signal within a range of voltages at the input.
1 . A power measurement circuit comprising:
a transconductance rectifier arrangement including an input and configured to receive a modulated sinusoidal input voltage signal; and
an averaging filter for producing a time averaged DC output signal proportional to the mean square of the voltage at the input of the transconductance rectifier arrangement and representative of the average power of the input voltage signal within a range of voltages at the input.
2 . A power measurement circuit according to claim 1 , wherein the averaging filter includes a RC filter.
3 . A power measurement circuit according to claim 2 , further including a single-ended input to the transconductance rectifier arrangement for receiving the modulated sinusoidal input voltage signal.
4 . A power measurement circuit according to claim 1 , wherein the averaging filter includes an RC filter for producing a time averaged DC output voltage signal as a function of the output current of the transconductance rectifier arrangement and representative of the average power of the input voltage signal within a range of input voltage signals.
5 . A power measurement circuit according to claim 1 , further including a DC bias impedance arrangement configured to apply a DC bias to the input of the transconductance rectifier arrangement and configured to prevent shorting of the modulated sinusoidal input voltage signal.
6 . A power measurement circuit according to claim 1 , wherein the transconductance rectifier arrangement includes a first rectifier element coupled to the averaging filter for generating a first output voltage representing (a) the mean square voltage at the input of the transconductance rectifier arrangement and (b) a reference voltage, and a second rectifier element coupled to an impedance for generating a second output voltage representing the reference voltage, the power measurement circuit further including an output for providing an output signal representing the mean square voltage as a function of the difference between the first output voltage and the second output voltage.
7 . A power measurement circuit according to claim 6 , further including a current mirror including one transistor element for generating a first reference current, and at least one other transistor element forming the first rectifier element of the transconductance rectifier arrangement so that a reference current is generated through the first rectifier element that is directly proportional to the first reference current.
8 . A power measurement circuit according to claim 6 , wherein the first and second rectifier elements each form a first stage, further including at least one additional rectifier element coupled to each of the first and second rectifier elements so that each forms a respective second stage so as to extend the range of input voltage signals in which the time average DC output signal is proportional to the mean square of the voltage at the input of the transconductance rectifier arrangement and representative of the average power of the input voltage signal.
9 . A power measurement circuit according to claim 8 , further including an offset voltage source coupled between each of the first rectifier and the second rectifier elements of the first stage on the one hand, and each of the corresponding rectifier elements of the second stage on the other hand.
10 . A power measurement circuit according to claim 1 , wherein the transconductance rectifier arrangement includes a common emitter transconductance rectifier.
11 . A power measurement circuit according to claim 1 , wherein the transconductance rectifier arrangement includes a common base transconductance rectifier.
12 . A power measurement circuit according to claim 1 , wherein the transconductance rectifier arrangement includes a npn transconductance rectifier.
13 . A power measurement circuit according to claim 1 , wherein the transconductance rectifier arrangement includes a pnp transconductance rectifier.
14 . A power measurement circuit according to claim 1 , wherein the transconductance rectifier arrangement includes a p-channel MOSFET transconductance rectifier.
15 . A power measurement circuit according to claim 1 , wherein the transconductance rectifier arrangement includes a n-channel MOSFET transconductance rectifier.
16 . A power measurement circuit according to claim 1 , wherein the transconductance rectifier arrangement includes a p-channel JFET transconductance rectifier.
17 . A power measurement circuit according to claim 1 , wherein the transconductance rectifier arrangement includes a n-channel JFET transconductance rectifier.
18 . A power measurement circuit according to claim 1 , wherein the transconductance rectifier arrangement includes a p-channel MESFET transconductance rectifier.
19 . A power measurement circuit according to claim 1 , wherein the transconductance rectifier arrangement includes a n-channel MESFET transconductance rectifier.